1. Field of the Invention
The present invention relates to a laboratory refrigerator, in particular a refrigerated incubator having temperature control for the circulating air, comprising an inner basin defining a useful storage volume, an outer basin surrounding the inner basin and forming a chamber therebetween, with the air being removed from the useful storage volume by means of a fan, the temperature being controlled in the chamber and conveyed back into the useful storage volume via apertures in the walls of the inner basin, and a refrigerating unit, the evaporator of which is supplied with the circulating air.
2. Description of the Related Art
In a known refrigerated incubator of this type, the air of the useful storage volume is circulated by means of a fan via a chamber formed between the inner basin and the outer basin. In order to regulate the temperature of the air, firstly heating elements and secondly the evaporator of a refrigerating unit are provided in this chamber.
In such known incubators the evaporator is constructed as a finned evaporator around which the circulating air flows. The fins of the finned evaporator provide a large surface for heat-exchange in order to provide for effective cooling of the circulating air. However, the tight arrangement of the fins complicates cleaning, which may be particularly problematical if biological material treated in the refrigerated incubator is spilt. The sharp-edged fins also represent a risk of injury during cleaning. In addition, condensation may occur, in particular on the pipes of the finned evaporator, resulting in the circulated air being dehumidified, which is undesirable. Moreover, as the finned evaporators only have a relatively small thermal capacity, their temperature displays relatively large variations, which in turn results in temporal and spatial inaccuracies in the temperature of the air in the useful storage volume.
In order to avoid the dehumidification of air in the useful storage volume, it is known to surround the useful storage volume with a closed jacket, in which the air is subject to temperature regulation and is circulated (e.g. refrigerated incubator BK 6160 of the company Heraeus). As no exchange of air occurs between the useful storage volume and the jacket, the air in the useful storage volume does not come into direct contact with the evaporator of the refrigeration unit and hence is only slightly dehumidified.
In this known refrigerated incubator only the air in the jacket surrounding the useful storage volume is subject to direct temperature regulation. The air in the useful storage volume is only subject to temperature regulation by thermal exchange with the air in the jacket via the wall of the inner basin. This provides poor energy transmission between the evaporator or respectively the heating elements and the air in the useful storage volume, so that the temperature regulation in the useful storage volume is sluggish. When the door of the refrigerated incubator is opened, such long recovery times ensue that it is scarcely possible to store the material in the refrigerated incubator under undisturbed temperature conditions.